Let's call an arrayAamountain if the following properties hold:

• A.length > = 3
• There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1]

Given an array that is definitely a mountain, return any i such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].

Example 1:

Input: 
[0,1,0]
Output: 
1

Example 2:

Input: 
[0,2,1,0]
Output: 
1

Note:

1. 3 < = A.length < = 10000
2. 0 < = A[i] < = 10^6
3. A is a mountain, as defined above.

class Solution {
    public int peakIndexInMountainArray(int[] A) {
        int n = A.length;
        int start = 1, end = n - 2;

        while (start + 1 < end){
            int mid = start + (end - start) / 2;

            if (A[mid] > A[mid - 1] && A[mid] > A[mid + 1]) return mid;
            else if (A[mid] >= A[mid - 1] && A[mid] <= A[mid + 1]) start = mid;
            else end = mid;
        }

        if (A[start] > A[end]) return start;
        else return end;

    }
}